How do I make fastfetch display an array of strings where some of them are colored differently and are in bold?

[thickmelon]

So I wanted to make fastfetch display a custom line with a fake OS name like so:

{
  "$schema": "https://github.com/fastfetch-cli/fastfetch/raw/dev/doc/json_schema.json",
    "display": {
        "constants": [
            "OS", // {$1}
            "dumbname_OS 21.3 x86_64"  // {$2}
        ]
    },
  "logo"
  "modules": [
    "title",
    "separator",
      {
            "type": "custom",
            "color": {
                "1": "red",
                "2": "white"
            },
            "format": "{$1}: {$2}!" // print "OS: dumbname_OS 21.3 x86_64"
        }
}

However, no matter what I do, the entire sentence "OS~64" just follows the default text color that I chose, as if it just ignores the color part. What part did I get wrong?

Also, is there any way to make one of those strings be in bold font?

[CarterLi]

{
    "type": "custom",
    "key": "OS",
    "format": "dumbname_OS 21.3 x86_64"
}

[CarterLi]

"{#1}dumbname_OS 21.3 x86_64" // bold

[thickmelon]

THANK YOU!!